Vitol Group and China Petroleum & Chemical Corp, known as Sinopec, are the two final bidders competing to buy Chevron Corp's South African assets, which could be worth about $1 billion, according to people familiar with the matter.

French oil major Total SA and Swiss commodity trader Gunvor Group Ltd have dropped out of the bidding, the people said, asking not to be identified as the information is private. Chevron plans to make a decision on the winner in the coming weeks, though the sale talks could still falter, the people said.

US oil producer Chevron offered to sell a 75 percent stake in its South African unit earlier this year as part of a three-year divestment program announced in 2014. The business includes a 110,000-barrel-a-day refinery in Cape Town and a lubricants plant in the eastern port city of Durban, as well as more than 800 Caltex service stations. The sale may fetch about $1 billion, people familiar with the matter said in March.

Andrea Schlaepfer, a London-based spokeswoman for Vitol, the world's biggest independent oil trader, declined to comment on the matter. Total and Gunvor also declined to comment. A representative of Sinopec, declined to comment.

"The process initiated by Chevron Global Energy Inc to solicit expressions of interest for its 75 percent shareholding of Chevron South Africa Proprietary Limited is ongoing," Braden Reddall, a Chevron spokesman, said.